agent_x007 was kind enough to provide functional info from his build to get me as far as I did with my BIOS work. That was quite some time ago. It was enough to verify that the microcode for this processor was present in the beta BIOS builds for the ASUS board we're talking about.

scali, I think you're right in terms of how far the boot process goes. I expect any BIOS is essentially going to run basic x86 instructions in order to work with any intel processor, then in boot phase will move to the specific set that the microcode dictates. At that point the software will have to support the configuration and it fails. agent_x007's 900 series chipset is a known quantity in terms of supporting these capabilities. I might have another go at it at some point, but I'm pretty satisified with my current group of builds.

I'm not able to compose or reply to PMs due to lack of enough participation? WTF? Seriously? Ok...whatever. 🙄

Anyhow...I just got a PM from @max1024 asking me if I'm using 4GB DDR2 sticks on the P4i945GC. No, just 2 x 2GB at the moment. I don't know if this board will run 4GB sticks. And I don't have any to try it with. I'd be mildly interested to know if it can too though. But somehow I doubt it. At any rate...Intel's specs say 4GB max(if I'm interpretting that right, sort of confused on why it seems to say 2GB max for the 82945GC, when I'm running 4GB on it). So I don't know what the point would be. Since, at best, you would only be able to run 1 x 4GB single channel. Which would suck(compared to 2 x 2GB dual channel).

Maximum memory size: 
4 GB for 82945G GMCH and 82945P MCH 
2 GB for 82945GZ/82945GC GMCH and 82945PL MCH

https://www.intel.com/Assets/PDF/datasheet/307502.pdf

I think it MIGHT be possible, because Memory Remap option is present.
However, 4GB+ memory requires 64-bit CPU, without it you will be limited to 3,5GB max. either way (regardless if 8GB is stable ot not).

Which limits both possible use cases (personally I think 8GB is a bit overkill for single core P4 at ~3,5GHz), and people that can use it (there are not that many 64-bit PGA 478 around).

There are some 32-bit CPUs that support PAE. But there aren't any that are compatible with the P4i945GC...AFAIK. I'm venturing off into that realm very soon, when I get the ASUS CT-479 adapter I just ordered. Which I plan to run some s479 Pentium M Dothans with on my P4P800-VM. It's only capable of 4GB max too. But Dothans support PAE. So hopefully I'll be able to use all 4GB of it now(if I'm understanding correctly how that works). 😀

Can PAE support help when BIOS can't see all 4GB of RAM as usable ?

I would guess not. But I don't really know how any of that works exactly. I've only just recently had any 32-bit systems with 4GB capable motherboards. Just this P4P800-VM and P4i945GC. Which I've only had for a couple months(more like a month with the P4i945GC). So...it's all new to me. As sad as that sounds...😒

Probably has something to do with that memory remap deal you mentioned I presume? I'll google it. No need to spoon feed the noob. 😁

agent_x007 wrote:

Can PAE support help when BIOS can't see all 4GB of RAM as usable ?

It's odd. Because the first time I booted up with a PM 740(w/ hardware PAE support) and the CT-479 on my P4P800-VM, the POST screen and System Info in the BIOS showed an additional ~400MB of RAM(of the 4GB that's installed) was available. 3711MB vs. 3327MB(which is all it's ever showed with any other processor installed). It wouldn't boot into Windows(can't recall why) though. So I never got to see if it really had that much more RAM that was "usable" in Windows. Anyhow...I can't make it repeat the behavior after that first boot. Now it just shows the same 3327MB every time(like it always has). And enabling PAE in XP doesn't seem to make any difference. It still shows the same 3.25GB it always has in System Properties. It does show the words "Physical Address Extension" below that now. Which might mean something. What I don't know...

Soooo...I don't know what to think about it. It almost seemed like it was going to work there for a minute. But I guess not...weird. 😒

I've still got a PM 780 to install and try out with it. Maybe it'll do it again with that one. We'll see. Gonna be running Windows 7 32-bit with 'em too. Which shouldn't make any difference. But who knows?

I have one of these chips, but on my S478 (Gigabyte 8KNXP, i875P chipset) board, I've been unable to actually boot into a 64 bit operating system. It detects the CPU just fine, CPU-Z under a 32-bit operating system will show the EM64T flag, yet everytime I try to boot into a 64-bit OS, it'll try, but by the time the OS' kernel jumps into action, the system either fully freezes or reboots. So these CPUs can be fickle to actually use for 64-bit stuff if your board isn't set up for it.

That's more or less pointless anyway.

More or less...I suppose. 🙄 Unless you want to run 64-bit apps. Then it very well does have a point.

Anyhow...I just figured out something with the PAE situation. Apparently it DOES work. Sometimes. If I do the right things to make it so. Or rather don't do the wrong things. Of which I'm not entirely sure what those are. But I digress. Long story short...it has something to do with how I configure my BIOS settings after clearing the CMOS. After resetting the BIOS it suddenly shows the extra ~400MB I spoke of.

In the BIOS.

And in Windows.

Not sure how I never noticed that until now... 😕. I could swear I tried that before and it did nothing. But like I said, I can make it NOT work by changing some BIOS setting(s). I can't think of which one(s) it would be. All I know at this point is it isn't setting the date and/or time.

Here's what that looks like.

BIOS tweaks probably can free up some reserved address space.
Unfortunately both 875P and 945P/G chipsets does not feature address remap over 4 Gb. PAE is completely useless too, due to the 4 Gb hard limit of the chipset and no support for buffered modules (2gb).

Unless you want to run 64-bit apps.

By the time 64-bit support started to become mandatory, Prescott was already ancient history. Horribly slow ancient history with 3.5 Gb RAM limitation.